Ar-halo-ar(t-alkyl)styrenes polymers

ABSTRACT

Ar-halo-ar(t-alkyl)styrenes, e.g., 2-chloro-4-(t-butyl)styrene, polymerize to form materials having unusually high temperature resistance. Additionally, compositions of such monomers, unsaturated polyesters and free-radical generating catalysts cure at lower temperatures and in less time than similar compositions containing conventional styrene monomers.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.534,391, filed Dec. 19, 1974, which in turn is a division of applicationSer. No. 94,578, filed Dec. 2, 1970 and now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to ar-halo-ar-alkylstyrene monomers, polymers andcurable molding compositions containing such monomers.

Polymers of styrene and various ring substituted styrenes are known tobe useful in molding applications and the like. In many molding andsimilar applications, however, the conventional styrene polymers do notpossess enough heat resistance and/or the ability to be cured rapidly.

Also it is known to prepare curable molding compositions ofcrosslinkable polymers, e.g., unsaturated polyesters, and styrenemonomers. In curing such compositions with the use of free-radicalgenerating catalysts, e.g., t-butyl perbenzoate, t-butylperoctoate,dicumyl peroxide and the like, and heat, it is greatly desirable toeffect complete curing within a relatively short period of time atminimum temperature. In many applications, it is also desirable that theresulting cured compositions exhibit resistance to high temperatures andat least a minimum degree of flame resistance.

While styrene and many known substituted styrene monomers impartdesirable qualities to the cured compound such as stiffness, the timerequired to gel such curable compositions and the temperature increaseduring curing are often excessive and therefore uneconomical.Additionally, exposure to the relatively high temperatures during curingoften has a deleterious effect on the cured product, e.g., the existenceof thermal stresses in the polymers of the cured product when suchpolymers are cooled to use temperatures. Such high temperatures duringcuring necessitate the employment of massive pressure equipment in orderto make good moldings.

In view of the foregoing disadvantages of conventional styrene polymersand of curable compositions employing styrene or conventional styrenemonomers, it would be highly desirable to provide monomers (1) whichpolymerize to heat resistant materials and (2) which, when substitutedfor styrene in conventional curable compositions, enable thecompositions to gel in shorter times and to cure at lower temperatures.Such monomers would offer the great commercial advantage of enabling theuse of fast mechanical presses employing essentially contact pressuresinstead of slow hydraulic presses.

SUMMARY OF THE INVENTION

In accordance with this invention, there are provided novelar-halo-ar-(t-alkyl)styrene monomers which polymerize to form materialshaving high heat resistance. Curable compositions of these monomers withcrosslinkable polymers and free radical generating catalysts gel in lesstime and cure at lower temperatures than do conventional compositionscontaining styrene.

The novel styrene monomers of the present invention are represented bythe general structural formula: ##STR1## wherein R₁ is hydrogen or alkylhaving 1 to 2 carbon atoms; R₂ is a tertiary alkyl having from 4 to 8carbon atoms and is in a ring position para or meta to the ethylenic##STR2## group; X is chloro, bromo or fluoro and is in an open ringposition; and a is one or two. By "open ring position" is meant a ringposition which is not occupied by either the ethylenic group or R₂ andwhich is not sterically hindered by either or both of said groups.

The ar-halo-ar-(t-alkyl)styrenes, particularly thear-halo-ar-(t-butyl)styrenes, are surprisingly more stable when exposedto heat than are the ar-halo-ar-(n-alkyl)styrenes. As a result of thissurprising thermal stability, the monomers of this invention whenpolymerized do not contain significant amounts of cross-linked polymer,often called gels. The absence of such gels in structural polymers ofthis type is important to render them usfeul in many applications, e.g.,moldings, foams, films, coatings and similar articles, wherein thepresence of gels considerably weaken the article and/or deleteriouslyeffects its appearance. Needless to say, the presence of gels in suchpolymeric materials renders them much more difficult, if not impossible,to extrude or mold. In addition, the tendency of monomers to form gelsunder normal polymerization conditions causes problems in thepolymerization process, e.g., buildup of hydrocarbon-insoluble productin the polymerization reactor which leads to frequent shut-down of theprocess to clean the reactor.

As stated hereinbefore, the ar-halo-ar-(t-alkyl)-styrenes, particularlythe ar-bromo-ar-(t-alkyl)styrenes, when polymerized exhibit surprisinglyhigher heat resistance (higher melting points) and reduced burningcharacteristics than do the polymers of ar-(t-alkyl)styrenes. As aresult of such higher heat resistances, such polymers can be formed athigher temperatures at which water can be effectively employed as ablowing agent.

Curable compositions effectively employing the foregoing novel monomerscomprise a crosslinkable material, ar-halo-ar-(t-alkyl)styrene monomerand preferably a free-radical generating catalyst. Such curablecompositions are particularly useful in the production of large moldedarticles such as auto bodies, aircraft parts, truck and bus bodies andparts, construction materials and the like. These compositions areparticularly useful in the production of thick parts wherein cureexotherm can be damaging during rapid cure. The low shrinkage of thenovel monomers during polymerization also enhances the properties of thecured compositions as compared to known monomers.

Polymers of the novel monomers of this invention are useful in theproduction of shaped articles requiring high heat resistance such aselectrical motor and appliance housings, contact pressure moldings,plastic parts to be painted and then oven cured, automobile hoods, hullsfor deep sea vessels, structural panels and beams as well as foams,architectural applications, films, large complex unimoldings andlaminates for electrical and electronic appliances, glassfiber-reinforced articles, and the like.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred ar-halo-ar-(t-alkyl)styrene monomers of this invention arerepresented by the following structural formulas: ##STR3## wherein R₁ ishydrogen, methyl, or ethyl; R₂ is tertiary alkyl having from 4 to 8carbon atoms, perferably tertiary butyl, and X is fluoro, chloro orbromo, preferably chloro or bromo.

Exemplary tertiary alkyl groups include t-butyl; t-pentyl; tertiaryhexyl groups (hereinafter called t-hexyl), e.g., tertiary alkyl groupshaving 6 carbon atoms such as 3-methylpent-3-yl, 2-methylpent-2-yl and2,3-dimethylbut-2-yl; tertiary heptyl groups, (hereinafter calledt-heptyl), i.e., tertiary alkyl groups having 7 carbon atoms, such as3-methylhex-3-yl, 2-methylhex-2-yl, 2,3,3-trimethylbut-2-yl, and2,3-dimethylpent-2-yl, 2,4-dimethylpent-2-yl and 2,3-dimethylpent-3-yl;and tertiary octyl groups (hereinafter called t-octyl), i.e., tertiaryalkyl groups having 8 carbon atoms, such as 2-methylhept-2-yl,3-methylhept-3-yl, 4-methylhept-4-yl, 2,3,3-trimethylpent-2-yl,2,4,4-trimethylpent-2-yl, 2,3,4-trimethylpent-2-yl,2,3,4-trimethylpent-3-yl, 2,2,3-trimethylpent-3-yl,2,3-dimethylhex-2-yl, 2,4-dimethylhex-2-yl, 2,5-dimethylhex-2-yl,2,3-dimethylhex-3-yl, 3,4-dimethylhex-3-yl, 3,5-dimethylhex-3-yl,2-methyl-3-ethylpent-3-yl, and 2-methyl-3-ethylpent-2-yl.

Examples of preferred ar-halo-ar-alkylstyrenes are2-chloro-4-(t-butyl)styrene, 2-bromo-4-(t-butyl)styrene,2-chloro-4-(t-pentyl)styrene, 2-bromo-4-(t-pentyl)styrene,2-chloro-4-(t-hexyl)styrene, 2-bromo-4-(t-heptyl)styrene,2-chloro-4-(t-octyl)styrene, 2-chloro-5-(t-butyl)styrene,2-bromo-5-(t-butyl)styrene, 2-chloro-5-(t-pentyl)styrene,2-bromo-5-(t-pentyl)styrene, 2-chloro-5-(t-hexyl)styrene,2-bromo-5-(t-heptyl)styrene, 2-chloro-5-(t-octyl)styrene,4-chloro-3-(t-butyl)styrene, 3-chloro-5-(t-butyl)styrene,3-bromo-5-(t-butyl)styrene, 3-chloro-5-(t-pentyl)styrene,3-bromo-5-(t-hexyl)styrene, 3-chloro-5-(t-octyl)styrene,3-bromo-5-(t-heptyl)styrene, 2,3-dichloro-5-(t-butyl)styrene,2,3-dichloro-5-(t-pentyl)styrene, 2,3-dibromo-5-(t-butyl)styrene,2,3-dichloro-5-(t-pentyl)styrene, and the like.

Examples of suitable ar-halo-ar-(t-alkyl)styrenes contemplated in thepractice of this invention are 2-fluoro-4-(t-butyl)styrene,2-fluoro-5-(t-pentyl)styrene, and similar ar-halo-ar-(t-alkyl)styrenes.Also included are 2-chloro-4-(t-butyl)-α-methylstyrene,2-bromo-4-(t-butyl)-α-ethylstyrene, 2-bromo-5-(t-pentyl)-α-methylstyreneand other ar-halo-ar-(t-alkyl)-α-methyl- and -α-ethylstyrenes.

The foregoing styrene monomers can be made by many different techniques,and this invention includes the foregoing monomers made by any method.

Generally, however, preparation of the foregoing monomers whereinhalogen is bromo or chloro is advantageously carried out in thefollowing steps:

1. alkylating ethyl benzene with suitable olefin, e.g., isobutylene, orsuitable t-alkyl halide, e.g., t-butyl chloride, t-amyl chloride, etc.;

2. halogenating the aromatic ring of the resulting ar-alkylethylbenzenewith free halogen or similar halogenating agent;

3. oxidizing the resulting ar-halo-ar-alkyl ethylbenzene to thecorresponding ar-halo-ar-alkyl acetophenone;

4. reducing the acetophenone to the corresponding alcohol; and

5. dehydrating the alcohol to form the desired styrene monomer,sometimes a mixture of two or more ar-halo-ar-alkyl styrene monomers.

In the preparation of monomers wherein halogen is fluoro, the aromaticring is fluorinated by replacing ring-substituted bromo or chloro withfluoro using a fluoride salt such as potassium fluoride. To preparemonomers wherein R₁ is alkyl, an acetophenone having the desiredsubstituents is reacted with alkyl magnesium bromide to form the alcoholwhich can be dehydrated to the desired α-alkylstyrene.

The desired styrene monomer can be isolated by known techniques andemployed in essentially pure form or the isomeric mixture of suchmonomers can be employed with nearly the same results. The foregoingsteps of alkylation and halogenation of aromatic rings are well known asare the conditions of such reactions which will yield substantialamounts of any one of the aforementioned monomers.

Illustratively, ar-halo-ar-(t-alkyl)styrenes, particularly the2-halo-ar-(t-alkyl)styrenes wherein halo is chloro or bromo, areprepared by the stepwise manner of

1. alkylating ethyl benzene with a suitable olefin, e.g., isobutylene,in the presence of sulfuric acid in accordance with the method ofIpatieff et al., JACS, Vol 58, 919 (1936);

2. halogenating the aromatic ring of the resultingar-(t-alkyl)ethylbenzene with free halogen in the presence of Lewis Acidsuch as tin tetrachloride;

3. oxidizing the resulting ar-halo-ar-(t-alkyl)ethylbenzene to a mixtureof the corresponding acetophenone-alcohol by the method of H. J. Sanderset al. Ind. and Eng. Chem., Vol 45, 2 (1953);

4. reducing the mixture by catalytic hydrogenation to the correspondingalcohol; and

5. dehydrating the alcohol with a dehydration catalyst, such as silicagel, alumina or titania, to form ar-halo-ar-(t-alkyl)styrene. In caseswherein halo is fluoro, the ar-chloro-ar-(t-alkyl)ethylbenzene isreacted with potassium fluoride in accordance with the method of Fingeret al., JACS, Vol 78, 6034 (1956). In cases wherein alkyl is primary orsecondary, acylation is carried out in the manner described in OrganicSyntheses, Collective Vol 2, 3-5 (1943).

Ar-halo-ar-(t-alkyl)styrenes of this invention polymerize readily underconditions conventionally employed for polymerizing styrene. Forexample, the foregoing styrene monomers polymerize when subjected toconditions of conventional free-radical catalyzed mass, suspension- andemulsion-polymerization techniques and of conventional ionicpolymerization techniques.

Representative catalysts employed in free-radical catalyzedpolymerizations include azo and peroxide-types, e.g., peroxides such asbenzoyl peroxide, hydroperoxides such as t-butyl hydroperoxide,per-acids such as perbenzoic acid, peresters such as t-butyl peroctoateand azo compounds such as azobisisobutyronitrile, with oil solublecatalysts such as benzoyl peroxide and dicumyl peroxide being employedin suspension and mass polymerization and water soluble peroxides suchas potassium persulphate and known redox-catalytic systems such ascumene hydroperoxide, urea-polyformaldehyde and ferric trichloride beingemployed in emulsion polymerization. Free radical catalyzedpolymerization is readily effected at temperatures of from about roomtemperature to about 200° C under atmospheric to superatmosphericpressure at catalyst concentrations of 0 in the case of thermalinitiation to about 5 weight percent based on weight of monomers,preferably from about 0.01 to about 5 weight percent of catalyst in pureform or in an inert solvent for the catalyst. Thermal initiationgenerally occurs at temperatures between 60°-120° C.

Representative ionic catalysts include lithium based catalysts, e.g.,metallic lithium, alkyl lithium and other lithium compounds, and Zieglercatalysts, e.g., reducible halide of titanium or vanadium in combinationwith aluminum trialkyl, or diethylaluminum chloride, or lithium aluminumhydride. Ionic polymerization is advantageously carried out in an inerthydrocarbon solvent such as lower alkane or lower aromatic hydrocarbonat temperatures in the order of about -20° to about 140° C underpressures ranging from atmospheric to superatmospheric and in thepresence of from about 1 to 200 ppm of ionic catalyst based on weight ofmonomers. Polymerization of similarly effected by cationic catalysts attemperatures from -100° to 100° C in the presence of the etherates ofboron trifluoride and aluminum trichloride or in the presence of Zieglercatalysts such as the reaction product of reducible transition metalcompounds such as titanium tetrachloride or trichloride and reducingorgano metallic compounds such as triethyl aluminum or diethylaluminumchloride.

Under one or more of the aforementioned polymerization techniques, thear-halo-ar-(t-alkyl)styrenes of the present invention are copolymerizedwith one or more of the following monomers: otherar-halo-ar-(t-alkyl)styrenes as described hereinbefore; themonovinylidene carbocyclic aromatic monomers such as styrene,α-methylstyrene, ar-t-butylstyrene, ar-chlorostyrene, ar-bromostyrene,ar,ar-dichlorostyrene, ar,ar-dibromostyrene, ar-methylstyrene,ar,ar-dimethylstyrene, ar-methoxystyrene, vinylbenzyl chloride,ar-isopropylstyrene, ar-ethylstyrene,divinylbenzene,ar,ar-diisopropenylbenzene and ar-vinyl-ar-isopropenylbenzene; theconjugated aliphatic dienes such as butadiene, isoprene,2,3-dimethylbutadiene, and cyclopentadiene; the α-monoolefins andhalogenated α-monoolefins such as ethylene, propylene, butene-l,isobutylene, 2-methyl pentene-1, vinylidene chloride; the lower alkyl orhydroxyalkyl esters of α,β-ethylenically unsaturated mono- anddi-carboxylic acids such as ethyl acrylate, methyl methacrylate,n-propyl itaconate, diethyl maleate dimethyl fumarate, n-butyl hydrogenmaleate, n-pentyl ethacrylate, n-octyl acrylate, iso-butyl acrylate,2-hydroxyethyl acrylate n-dodecyl methacrylate and other esters whereinalkyl has from 1 to 24 carbon atoms and hydroxyalkyl has from 1 to 12carbon atoms; other polymerizable esters such as methylar-vinyl-benzoate and ethyl ar-vinyl-benzoate, the α,β-monoethylenicallyunsaturated nitriles and amides such as acrylonitrile,methacrylonitrile, ethacrylonitrile, fumaronitrile, acrylamide,methacrylamide and fumaramide; other polymerizable amides and nitrilessuch as ar-cyanostyrene and vinylbenzamide; the α,β-ethylenicallyunsaturated mono- and di-carboxylic acids such as acrylic acid,methacrylic acid, maleic acid and anhydride fumaric acid, itaconic acid,and citraconic acid; other ethylenically unsaturated carboxylic acidssuch as vinylbenzoic acid.

Homopolymers and copolymers of the ar-halo-ar-(t-alkyl)styrenes arenormally solid, thermoplastic materials having heat distortiontemperatures generally higher than corresponding homopolymers andcopolymers of styrene or other previously known monovinylidenecarbocyclic aromatic monomers. As a general rule the polymers ofar-halo-ar-(t-alkyl)styrenes can be molded, extruded, milled orotherwise fabricated into useful articles according to known techniquesfor fabricating conventional styrene polymers with the exception thatsomewhat higher temperatures must be employed.

The improved curable compositions of the present invention comprise acrosslinkable material, an ar-halo-ar-(t-alkyl)styrene as describedhereinbefore and preferably a catalytic amount of a free-radicalgenerating catalyst. By crosslinkable material is meant a monomer orpolymer containing at least one ethylenically unsaturated bond which ispolymerizable with a vinylidene aromatic carbocyclic monomer such asstyrene. Preferably said compositions comprise from about 5 to about 70weight percent of the crosslinkable material, from about 95 to about 30weight percent of the ar-halo-ar-(t-alkyl)styrene and the catalyst.Usually the concentration of catalyst is from about 0.1 to about 4weight percent based on monomer.

In the improved curable compositions of this invention, thecrosslinkable materials employed therein are preferably crosslinkablepolymers such as the unsaturated polyesters.

For the purposes of this invention, the term "unsaturated polyesters" ismeant to include condensation reaction products of saturated orunsaturated polycarboxylic acids with polyhyric alcohols.

Exemplary polycarboxylic acids include the unsaturated dicarboxylicacids such as maleic, fumaric, itaconic, mesaconic, and citraconic andother polycarboxylic acids or anhyrides such as adipic, succinic,phthalic, isophthalic, terephthalic diglycolic, oxalic, sebacic,azaleic, maleic, glutaric, diphenic, tetrachlorophthalic,2,3-dicarboxy-1,4,5,6,7,7-hexachlorobicyclo[2.2.1]hept-5-eneanhydride,2,3-dicarboxy-5,8-endomethylene-5,6,7,8,-9,9-hexachloro-1,2,3,4a,5,8,8a-octahydronaphthaleneanhydride and the like.

Among the polyhydric alcohols suitably employed are the diols such asethylene glycol, propylene glycol, diethylene glycol, dipropyleneglycol, triethylene glycol, neopentyl glycol, propane-, butane-,pentane- and hexane-diols, trimethylene glycol, polyethylene glycol,polypropylene glycol, dimethylolpropane, also included are bisphenol-A,and hydrogenated bisphenol-A. Monofunctional alcohols, such as butanol,tetrahydrofurfuryl alcohol and ethylene glycol monobutyl ether, as wellas monobasic acids, such as benzoic, t-butylbenzoic, oleic, linseed oilfatty acid and dehydrated castor oil fatty acid may also be employed.Suitable crosslinkable polymers also include diene polymers,particularly elastomeric polymers of conjugated aliphatic dienes havingpendant vinyl groups on the polymer chain such as 1,2-polybutadiene,polyisoprenes and block copolymers of polymerized styrene andpolymerized conjugated dienes having pendant vinyl groups. Also includedin the crosslinkable materials are polyethylenic monomers such asdivinyl benzene, trivinyl benzene, diisopropenyl benzene,vinylisopropenyl benzene, divinyl toluene and the like.

Polymerization or gel catalysts useful for curing the improved curablecompositions of this invention are conventional free-radical generatingcatalysts such as peroxides, e.g., dicumyl peroxide di-t-butyl peroxide,t-butyl perbenzoate, t-butyl peroctoate, 2,2-bis-(t-butylperoxy)butane,benzoyl peroxide, lauroyl peroxide, and methyl ethyl ketone peroxide;azo compounds such as azobisisobutyronitrile, and the like. Promotersmay be used such as cobalt, manganese, iron, nickel, zirconium and thelike in the form of octoates naphthenates, or acetylacetonates which arecompatible with the monomeric material. Accelerators such asN,N'-dimethylaniline are optionally employed to shorten the total curetime for the aforementioned curable compositions. It is understood,however, that neither the catalyst nor the accelerator are required asthe curable compositions are readily cured by thermal initiation usingtemperatures from about 30° to about 120° C.

In addition to crosslinkable polymer, ar-halo-ar-(t-alkyl)styrene, andcatalysts, the curable compositions may also contain other monomerscopolymerizable with the styrene as such copolymerizable monomers areset forth hereinbefore. Exemplary copolymerizable monomers includestyrene, divinyl benzene, vinyl toluene, ar-(t-butyl)styrene,ar-chlorostyrene, ar-bromostyrene, ar,ar-dichlorostyrene,diisopropenylbenzene, vinyl isopropenylbenzene and other monovinylidenecarbocyclic aromatic monomers; ethylene, propylene, isobutylene andother α-monoolefins; diallyl maleate diallylphthalate triallylmellitate,ethyl acrylate, methyl methacrylate, isopropyl methacrylate, dimethylitaconate, ethylene glycol dimethacrylate, diethylene glycol acrylate,and other unsaturated esters; fumaronitrile, acrylonitrile,methacrylonitrile, acrylamide, methacrylamide, N-t-butyl methacrylamideand triallyl phosphate.

The curable compositions optionally contain other known additives, e.g.,magnesium oxide, chalk, clay, sand, antimony oxide, alumina trihydrate,silica, slate powder, dolomite barite, talc, zinc stearate, dyestuffs,fabrics and fibers of glass, synthetic resin, asbestos or textileproducts, compounds which give protection against light, heat or burningand the like.

Methods for curing conventional compositions containing unsaturatedpolyester, styrene monomer and catalyst are suitable for curing thecurable compositions of this invention. As an additional advantage ofthe present invention, the curable compositions thereof are rapidlygelled and cured in match-die molding of parts having large flatdimension and thickness. Curable compositions of the present inventioncan be cured at low or even contact pressure; and as a result, faster,more efficient mechanical presses can be substituted for the slowerhydraulic presses used in conventional match-die molding apparatus. As ageneral rule cure of the curable compositions of this invention can beeffected at mold or bath temperatures less than 300° F and in times of10 minutes or less.

The following examples are given to illustrate the invention and shouldnot be construed as limiting its scope. In the examples all parts andpercentages are by weight unless otherwise indicated.

EXAMPLE 1

A 1-liter jacketed continuous chlorination reactor equipped withstirrer, gas inlet tube, thermometer and feed inlet port is charged with975 g of ar-(t-butyl)-ethylbenzene (˜95% para-isomer) and 21 g ofanhydrous tin tetrachloride. Chlorine gas is fed at 400 cc/min into theapparatus maintained at 25°-50° C throughout the reaction. After 4.5hours reaction time, more of the ar-(t-butyl)ethylbenzene is fed intothe reactor at 328 cc/hr for 4 additional hours. Product is removed fromthe reactor, washed with 2% potassium hydroxide solution, and distilledto obtain ar-chloro-ar-(t-butyl)ethylbenzene (a mixture of 90 parts2-chloro-4-(t-butyl)ethylbenzene, 5 parts2-chloro-5-(t-butyl)ethylbenzene and5 parts other isomers in 90% yieldbased on unrecovered starting material).

A 600-g portion of the ar-chloro-ar-(t-butyl)-ethylbenzene and 5 g ofcobalt naphthenate solution (6% cobalt) are charged to a 1-liter,round-bottom, 3-necked flask equipped with a glass frit gas inlet tube,heating mantle, esterification water separator and a temperaturecontroller. The reaction mixture is heated to 125° C and oxygen isintroduced at ˜1.5 ft³ /hour for a total of 8 hours. The oxygen is shutoff and the product is analyzed by infrared spectroscopy and vapor phasechromatography and found to contain 20.4 percent ofar-chloro-ar-(t-butyl)acetophenone and 12 percent ofar-chloro-r-(t-butyl)α-methyl benzyl alcohol, with the remainingmaterial being starting material. The product is distilled under vacuumto obtain an alcoholketone mixture in 79% yield based on the unrecoveredstarting material. The mixture has an atmospheric boiling point of300°-320° C.

A 100-g portion of the alcohol-ketone mixture, 10 g of calcium hydroxideand 5 g of copper chromite are placed in a 500 cc hydrogenation bomb.The bomb is heated at 150° C for 1/2 hour under nitrogen and is thenclosed and purged three times with hydrogen. The pressure of the bomb isbrought to 500 psig with hydrogen and is heated at 150° C for four hourswith moderate agitation. The bomb is cooled to room temperature andhydrogen is vented. Analysis of the product with vapor phasechromatography confirms ˜90 percentar-chloro-ar-(t-butyl)-α-methylbenzyl alcohol.

A mixture of 50 g of ar-chloro-ar-(t-butyl)-α-methylbenzyl alcohol and50 parts of toluene is prepared. A reaction column (1 inch outsidediameter × 27 inches length) is filled to a bed height of 8 inches withsilica gel (8-10 mesh, 340 m² of surface area/g, 140A average porediameter) and sufficient amount of silicon carbide (6 mesh) is added tothe tube to increase total bed height to 16 inches. The reaction columnis heated to 350° C. Water preheated to 300° C and the mixture are addedsimultaneously into the silicon carbide end of the column at rates of 90ml/hr and 45 ml/hr respectively. An intimate admixture of steam and thealcohol mixture in vapor phase is formed and passes downward through thesilicon carbide preheated to 350° C which acts as a preheat section forthe vapor and then through the silica get to effect dehydration.Following passage through the silica gel, water and organic product arecondensed in the column, and collected. The dehydrated organic productis decanted, dried and distilled. The distilled product is determined byvapor phase chromatography to be ar-chloro-ar-(t-butyl)styrene (amixture of 92 pts 2-chloro-4-(t-butyl)styrene, 5 pts2-chloro-5-(t-butyl)styrene and 3 pts other isomers) at 99 percent orgreater purity. Overall yield on basis of amount of starting alcohol isgreater than 90 percent.

A 100-g portion of the ar-chloro-ar-(t-butyl)styrene, hereinafterreferred to as CTBS, is charged to a polymerization zone and contactedwith 0.2 g of t-butyl peroctoate at 85° C for 48 hours to provie a CTBShomopolymer having a Vicat softening point (ASTM D-1525-65T) at 163° C,a molecular weight of ˜105,000, and viscosity of 9.11 cps (10% solutionin toluene at 25° C).

A monomer mixture of 34.9 g of fumaronitrile and 65.1 g of the CTBS isplaced in a glass tube (1/2 inch dia × 36 inches length). The tube isheld under a vacuum for 5 minutes and then sealed with a flame. The tubeis placed horizontally in a steam bath for 3 days. The polymer isremoved from the glass tube, crushed and devolatilized in a vacuum ovenat 140° C for 24 hours. Analysis of the polymer yields 5.5% nitrogen and15% chlorine confirming a fumaronitrile/CTBS (31.5/68.5) copolymer. Thecopolymer has a Vicat softening point of 176°-180° C.

EXAMPLE 2

In a manner similar to Example 1, ar-bromo-ar-(t-butyl)styrene isprepared by brominating ar-(t-butyl)-ethylbenzene (a mixture of 95 ptsof para-isomer and 5 pts of meta-isomer). Accordingly, a b 5-liter,3-necked round bottom flask equipped with stirrer, condenser, andaddition funnel is charged ith 2000 g of the ar-(t-butyl)ethylbenzeneand 50 g of anhydrous tin tetrachloride. A 960-g portion of bromine isadded dropwise to the flask (covered with aluminum foil) with stirringat 25°-35° C over a 5-hour period. The reaction mixture is then stirredat 40° C for 1 and 1/2 hours to complete the reaction and the reactionproduct is poured onto ice and washed once with water and once with a 10percent aqueous solution of sodium carbonate.

The washed product is distilled under reduced pressure to obtainnar-bromo-ar-(t-butyl)ethylbenzene (a mixture of 95 pts2-bromo-4-(t-butyl)ethylbenzene and 5 pts of2-bromo-5-(t-butyl)ethylbenzene).

A 1000-g portion of the 2-bromo-ar-t-butyl ethylbenzene is passed over abed of alumina and then oxidized at 125° C in an apparatus similar tothe oxidation apparatus of Example 1 using 940 cc/min of oxygen and 10 gof cobalt naphthenate solution (6% cobalt). The reaction is stoppedafter 3-1/2 hours at ˜27% conversion. The product is washed with dilutesodium hydroxide, is then washed with water and is distilled underreduced pressure (B.P. 109° C at 0.6 mm Hg).

The resulting 2-bromo-ar-(t-butyl)acetophenone is reduced at roomtemperature in diethyl ether using lithium aluminum hydride as thereducing agent in accordance with the teaching of Vogel, A.I., Atextbook of Practical Organic Chemistry, 3rd ed., Longmans, Green & Co.,New York, pp. 877-879 (1956). A pale crystalline solid of2-bromo-ar-(t-butyl)a-methylbenzyl alcohol is obtained.

The resulting alcohol is dehydrated in accordance with the dehydrationprocedure of Example 1 to produce 2-bromo-ar-(t-butyl)styrene {95 pts2-bromo-4-(t-butyl)styrene and 5 pts 2-bromo-5-(t-butyl)styrene }containing about 2% of the starting alcohol. The2-bromo-ar-(t-butyl)styrene boils at 77.5°-80° C at 0.7 mm Hg and has arefractive index of 1.5598 at 25° C.

The ar-bromo-ar-(t-butyl)styrene, hereinafter referred to as BTBS, ispolymerized in a glass bomb at 100° C to provide a BTBS homopolymerwhich is a self-extinguishing, colorless solid soluble in toluene andhaving a Vicat softening point of 172°-174° C.

A monomer mixture of 50 parts of ar-(t-butyl)styrene and 50 parts of theBTBS are added to a bottle containing 0.2 part of t-butyl peroctoate.The bottle is purged with nitrogen, is sealed and is then subjected topolymerization conditions of 80° C for 72 hours to provide anar-(t-butyl)styrene/BTBS copolymer (approximately equimolar). Thepolymer is removed from the glass bottle, is crushed into a powder andis placed in a vacuum oven at 140° C for 24 hours to remove unreactedmonomer. The dried polymer is compression molded at 200° C into articleswhich are resistant to boiling water and are fire retardant.

EXAMPLE 3

Curable compositions of CTBS and BTBS provided in Examples 1 and 2,respectively, are prepared by dissolving two 50-pt portions ofdipropylene glycol maleate polymer (10 molecules of maleic acid/11molecules of dipropylene glycol, acid number of 50) in separate 50-ptportions of CTBS and BTBS. A 0.5-part portion of t-butyl peroctoate isadded to each of the two foregoing solutions and 10 g of each of the tworesulting mixtures are added to glass test tubes (18 mm dia × 150 mmlength). A thermocouple and stopper is inserted into each test tube andthe tubes are immersed in a heating bath at 240° F and clamped. The geltime, cure time and maximum temperature of each of the two curablecompositions are measured and recorded in Table I.

Several control compositions (C₁, C₂ and C₃) are similarly preparedusing styrene, ar-chlorostyrene, and ar-(t-butyl)styrene instead of CTBSor BTBS and are cured by the foregoing procedure. Gel times, cure timesand maximum temperatures of the control compositions are also measuredand recorded in Table I.

                                      TABLE I                                     __________________________________________________________________________    Run No.                                                                            Monomer                                                                             Gel Time,                                                                           Peak Cure                                                                             Cure Time,                                           (1)  (2)   Sec (3)                                                                             Temp, ° F (4)                                                                  Sec (5)                                                                                 Observation                                __________________________________________________________________________    1    CTBS  4.4   424     29    Lightly cracked, some pieces                                                  exceeding 1"×31/4 ", transparent         2    BTBS  5.0   396     37    Lightly cracked, some pieces                                                  exceeding 1"×1/2", transparent           C.sub.1 *                                                                          Sty   28.0  565     72    Heavily cracked, no piece greater                                             than 1/4" in any dimension,                                                   opaque                                         C.sub.2 *                                                                          CS    12.5  468     51    Heavily cracked, no piece greater                                             than 1/4" in any dimension,                                                   opaque                                         C.sub.3 *                                                                          TBS   11.5  475     61    Medium cracking, largest pieces                                               about 1/2"×1".                           __________________________________________________________________________     *Not an example of the invention                                              (1) Average of six runs.                                                      (2) CTBS - ar-chloro-ar-(t-butyl)styrene of Example 1                         BTBS - ar-bromo-ar-(t-butyl)styrene of Example 2                              Sty - styrene                                                                 CS - ar-chlorostyrene                                                         TBS - ar-(t-butyl)styrene                                                     (3) Gel time is determined using SPI Gel Test developed by the Standards      Committee of the Reinforced Plastics Division of the Society of the           Plastics Industry. See Lawrence, J.R., Polyester Resins, Reinhold             Publishing Corp., New York, pp. 37-38 (1960).                                 (4) Maximum temperature reached using SPI Gel Test.                           (5) Time interval between curable composition at 150° F and maximu     temperature using SPI Gel Test.                                          

EXAMPLE 4

A polymerizable composition is prepared by adding 66 g of an isomericmixture containinng 2-chloro-5-(t-butyl)-styrene and associated isomersto 34 g of maleic anhydride in 400 g of methyl ethyl ketone. Theisomeric mixture is prepared by first chlorinating b5-(t-butyl)ethylbenzene in accordance with the procedure set forth inExample 1 and subsequently oxidizing, hydrogenating and dehydrating thechlorinated material in accordance with the procedures of Example 1. Thecomposition is placed in a bottle which has been purged with nitrogenand is capped. The bottle is then heated in a water bath at 80° C and istumbled for 48 hours. The resulting heavy syrup in the bottle is dilutedto 5% solids with methyl ethyl ketone and is added dropwise to a coldmethanol with stirring. The resulting polymer precipitate is weighed anddried in a circulating air oven. The polymer gives a positive test forchlorine and is soluble in hot caustic confirming anar-chloro-5-(t-butyl)styrene/maleic anhydride copolymer. The copolymeris cast into a thin film which does not distort at 200° C.

EXAMPLE 5

A mixture of 85 g of 2-bromo-4-(t-butyl)styrene is added to 20 g ofacrylonitrile in a sample bottle. The sample bottle is placed on abalance in a fume hood and purged with nitrogen until the net weight is100. The liquid monomer mixture is then poured into 1/2 inch × 3 inchesglass ampoules until 1/2 full and sealed under vacuum. The tubes arethen placed in a glycol bath maintained at 110° C. After 48 hrs thetubes are placed in a circulating air oven at 140° C for 24 hours. Thetubes are removed and the glass shells are broken free of the polymer.The polymer is dissolved in methyl ethyl ketone and added dropwise tostirred methanol. The polymmer precipitate is filtered and dried in acirculting air oven. Analysis of the polymer for bromine and nitrogenconfirms a 2-bromo-4-(t-butyl)styrene/acrylonitrile copolymer. Thecopolymer is cast as a film which is found to be heat and fireresistant.

EXAMPLE 6

A polymerizable composition of 70 parts of an isomeric mixturecontaining 2,3-dichloro-5-(t-butyl)styrene and associateed isomers and30 parts of methylmethacrylate are placed in a glass tube (1/2 inch dia× 24 inches length) with 0.1 part of α,α'-azodiisobutyronitrile and thetube is sealed. The isomeric mixture is prepared by chlorinating3-(t-butyl)-ethylbenzene in accordance with Example 1 to formmonochlorinated material which is isolated by distillation andsubjecting the monochlorinated to the same chlorinating conditions toform the dichlorinated material which is subsequently oxidized,hydrogenated and dehydrated by the procedures of Example 1. Thepolymerizable composition is polymerized for 48 hours at 40° C. Thesealed tube is then placed in a glycol bath at 90° C for an additional24 hrs. The polymer after removal from the tube, is dissolved in methylethyl ketone to form a 5% solution of the polymmer. The 5% solution isadded dropwise to methanol with stirring. The precipitated polymer isdried in an air oven and is then injection molded into a lens shape. Thepolymer lens does not distort in boiling water.

EXAMPLE 7

The 2-bromo-4-(t-butyl)-α-methylstyrene is prepared by first brominating4-(t-butyl)ethylbenzene under the conditions set forth in Example 2 andsubsequently oxidizing the brominated material as in Example 2 to formthe corresponding acetophenone, reacting the acetophenone with methylmagnesium bromide under the conditions described in Vogel, A. I.Practicl Organic Chemistry, 813 (1956) and dehydrating the resultingalcohol by the procedure of Example 2. A 10-g portion of2-bromo-4-(t-butyl)-α-methylstyrene is dissolved in 85 g of methylenechloride. This mixture is charged to a flask equipped with stirrer whichflask is placed in a dry ice-acetone bath until cooled to about -50° C.Rapid stirring is continued as 0.1 g of conc. sulfuric acid (95%) isadded in one shot. The mixture is stirred an additional hour at -50° Cand then poured into methanol. The polymer precipitate is filtered,washed with methanol and dried in air. Analysis of the polymer confirmsa homopolymer of 2-bromo-4-(t-butyl)-α-methylstyrene.

EXAMPLE 8

2-bromo-b 5-(t-butyl)styrene is prepared by first brominating3-(t-butyl)ethylbenzene under conditions used in Example 2 and thenoxidizing, hydrogenating, and dehydratinng the brominated material as inExample 2. The 2-bromo-5-(t-buyl)styrene is then isolated from the otherisomers produced and a 77-g portion thereof is mixed with 23 g ofstyrene. The resulting mixture is polymerized as in Example 6. Thepolymer is compression molded at 200° C into hard, clear slabs. Analysisof the polymer confirms a styrene/1-bromo-5-(t-butyl)styrene (29.3/70.7)copolymer.

EXAMPLE 9

An isomeric mixture containing 2-chloro-4-(t-pentyl)styrene is preparedin accordance with Example 1 except that 4-(t-pentyl)ethylbenzene ischlorinated instead of ar-(t-butyl)ethylbenzene.

A polymerizable composition of 75 g of butadiene and 25 g of theisomeric mixture of 2-chloro-4-(t-pentyl)-styrene and associatedar-chloro-4-(t-pentyl)styrenes is emulsified in 180 g of water,containing 5 g of sodium stearate. A 0.3 g portion of potassiumpersulfate is added as a catalyst, 0.5 g of dodecylmercaptan is added asa chain terminating agent and 0.3 g of potassium bicarbonate is added asa buffer. The emulsion is transferred to a bottle which is purged withnitrogen, is capped and is placed in a rotating tumbler bath at 50° Cfor 12 hours. The unreacted monomers are stripped off, and the resultinglatex cast as a thin layer on a glass plate. The layer of latex is driedto a continuous film which is stripped from the glass plate. The filmexhibits elasticity and other properties similar to those of rubber.Analysis of the polymer confirms abutadiene/ar-chloro-4-(t-pentyl)-styrene copolymer (˜65/35).

EXAMPLE 10

A mixtue of 50 g of hydroxyapatite and 0.12 g of sodium dodecylbenzenesulfonate is added to 4000 g of water and the resulting aqueous mixtureis shaken until uniform and filtered into a stock bottle. A 100-gportion of this suspending media and a small crystal of sodiumdichromate are added to a citrate bottle which is then shaken. A monomermixture of 30 g of 2-chloro-4-(t-octyl)-styrene prepared in accordancewith Example 1 except that 4-(t-octyl)ethylbenzene is chlorinatedinstead of ar-(t-butyl)ethylbenzene and 30 g of ar-chlorostyrenecontaining 0.12 g of t-butylperoctoate and 0.03 g of t-butylperbenzoateis added to the water layer. The citrate bottle is purged with nitrogenand capped. The bottle is then shaken vigorously and the monomericmixture is polymerized in a tumbling glycol bath at 90° C for 8 hoursand then at 110° C for 8 additional hours. The resulting polymer beadsare collected on a filter and washed with quantities of dilute (0.05 N)hydrochloric acid and then with water. The beads are then dried and forma film when heat plastified in the platens of a molding press. This filmdoes not distort in boiling water.

EXAMPLE 11

A mixture of 10 parts of 2-bromo-4-(t-butyl)-styrene and 10 parts ofisobutylene are cooled and collected in 100 parts of liquid propane at-50° C. A 1-ml portion of boron trifluoride etherate solution (5%active) is added to the mixture. The monomers are polymerized at -40° C.The resulting polymer solution is added slowly to methanol and warmed toroom temperature. The polymr formed is pliable, soluble in hydrocarbonsolvents such as toluene and forms a film when dry. Analysis of thepolymer confirms an isobutylene/2-bromo-4-(t-butyl)styrene copolymer.

EXAMPLE 12

To a flask containing 300 g of a large particle size polybutadienelatex¹ (approximately 150 g of solid rubber) is added with stirring amixture of 1.2 g of potassium persulfate, 5.0 g of t-dodecylmercaptan,5.0 g of di-t-butyl-p-cresol, and 10 g of sodiumoctadecylsulfosuccinate, 5 g of a solution of tetrasodium ethylenediamine tetraacetate and 5 g of stearic acid. A monomeric materialconsisting of 200 g of acrylonitrile, 250 g of2-chloro-4-(t-butyl)styrene and 250 g of styrene is added continuouslydropwise to the heated (60° C), stirred latex composition over a periodof 6 hours. The resulting mixture is stirred for an additional hour at80° C. The resulting polymerizate is then filtered through a filter toremove a small amount of coagulum around the stirrer. The polymerizateis then poured thru a 12 mm 33 600 mm bed of polymer particles describedin U.S. Pat. No. 3,520,806 to remove any residual monomer.

12% cis 1,4-polybutadiene

74% trans 1,4-polybutadiene

11% vinyl 1,2-polybutadiene

3% polymerized styrene and divinyl benzene.

The polymerizate is then dried in a tray and then subjected toconditions of devolatilization in a heated vacuum oven. The polymerizatein the form of a cake is then crushed to a powder. A portion of thispowder is compacted on a two roll mill heated to 180° C and then moldedin a compression press (170° C) to 1/8inch thick dumbbell bars which aretested for impact strenght. The bars have notched impact strength asdetermined by ASTM D-256-47T of 3.4 ft-lbs/in and heat resistancegreater than 250° F under load. Test bars of conventionalacrylonitrile/butadiene/styrene terpolymer are severly deformed whensubjected to a temperature of 220° F under load. A 100-g portion of thepowder is intimately mixed in a twin shell blender with 100 g of a vinylchloride/vinylidene chloride (99/1) copolymer that has been previouslystabilized with 3 weight percent of dibutyl tinS,S'-bis-(3,5,5-trimethylhexylmercapto)acetate. The resulting powder mixis then heat plastified using heated rolls, to obtain a compacted formwhich is suitable for molding. A similar amount of the powder mix is feddirectly to a screw injection molding machine and molded into tabs.

EXAMPLE 13

A 30-part portion of a liquid hydrocarbon polymer having a viscosity inthe range of 4000-4500 poise at 77° F, a composition of about 20%styrene and 80% butadine with most of the butadiene being 1,2-polymerhaving pendant vinyl groups, specific gravity 0.915 and a refractiveindex 1.53 is added to 70 parts of ar-chloro-5-(t-butyl)styrene [amixture of 90 parts of 2-chloro-5-(t-butyl)styrene and 10 parts of3-chloro-5-(t-butyl)styrene]. Then a mixture of 4 parts of 50%divinylbenzene in ethylvinylbenzene and 4 parts of di-t-butylperoxideare added to the polymerizable material. The resulting resin mix is thencast between plates with a 1/16 inch spacer and cured to a crosslinkedpolymer at 150° C in a pressure press. The plastic formed is clear,hard, insoluble in most solvents and heat resistant. A similar portionof the resin mix is poured between and over 13 plies of fiberglass cloth(N0.181 weave) and cured in a press with 1/8 inch spacers at 150° C.After curing, the laminate is sawed into dumbbell shaped bars fortesting. The resulting laminates have tensile strength above 45,000 psi,notched impact strength of 17.4 ft-lbs, and outstanding heat resistance(Vicat softening point at 160° C).

EXAMPLE 14

A 30-part portion of a liquid hydrocarbon polymer of polymerizedbutadiene greater than 80 percent of 1,2-polymer in a hexane solution(50% polymer in hexane) is added to 70 parts of an isomer containing2-bromo-5-(t-hexyl)styrene and associated ar-bromo-5-(t-hexyl)styreneisomers. The isomer mixture is prepared in accordance with Example 2except that 5-(t-hexyl)ethylbenzene is brominated instead ofar-(t-butyl)ethylbenzene. This mixture is heated to no more than 40° Cunder vacuum to remove the hexane. Three parts of di-cumyl peroxide isadded to the mix and dissolved. This resin mix is divided into twoportions. One portion is crosslinked as in Example 13 and the otherportion is poured to fiberglass cloth and then cured also as in Example13. Both the crosslinked polymer and the laminate are fire retardant inaddition to being clear, hard, insoluble in most solvents and heatresistant.

EXAMPLE 15

A 10-part portion of a polybutadiene-type rubber made by anionicpolymerization using a lithium catalyst is added to a mixture of 5 partsof divinylbenzene and 42.5 parts of ar-chloro-4-(t-heptyl)styreneprepared by first chlorinating 4-(t-heptyl)ethylbenzene and thenfollowing the remaining procedures of Example 1 and 42.5 parts ofar-bromo-4-(t-hexyl)styrene prepared by first brominating4-(t-hexyl)ethylbenzene and then following the remaining procedures ofExample 2. A 2-part portion of di-t-butyl peroxide is added to theresulting resin syrup which is then divided into two portions. Oneportion is crosslinked as in Example 13 and the other portion is pouredas before on fiberglass cloth and cured also as in Example 13. Thecurable composition and the laminate cure very rapidly and exhibit heatresistance and fire retardancy.

EXAMPLE 16

A 50-part portion of a copolymer of about 75 weight percent of2-bromo-4-(t-butyl)styrene and about 25 weight percent of acrylonitrileis heat plasticized with 50 parts of polyvinyl chloride, containing 3weight percent of a commercially available sulfur containing organotincompound as stabilizer, by milling the materials on a pair of laboratoryrolls at a temperature of about 180° C for a period of about 20 minutesto form a homogeneous composition. The mixture is then removed from therolls, is allowed to cool to room temperature and is crushed to agranular form. Portions of the compositions are injection molded andtested for tensile strength, elongation and impact strength. Thereslting injection molded articles are found to have excellent tensilestrength, elongation and impact strength as compared to compositionsdescribed in U.S. Pat. No. 3,424,823.

EXAMPLE 17

A solution is prepared by dissolving in 74 parts of2-chloro-4-(t-butyl)styrene, 10 parts of stereospecific polybutadienerubber having a Mooney number ML 1+4 (212° F) of 35, i.e., FirestoneSynthetic Rubber and Latex Company, "Diene", consisting of over 90percent 1,4-structure and only about 7.5 percent vinyl structure(1,2-structure), the cis-1,4 configuration comprising 32 to 35 percentof the polymer, and which polybutadiene rubber is of narrow molecularweeight distribution. A 16-part portion of acrylonitirle is added to thesolution. The solution is heated in a closed elongated vessel and isagitated by rotating the vessel end over end to polymerize the monomerunder time and temperature conditions as follows: 3 days at 95° C; 3days at 115° C; and 1 day at 140° C. The polymer is removed from thecontainers and is ground to a granular form. The ground polymer isheated in a vacuum oven at 150°-160° C under 1.5 millimeters absolutepressure for a period of 16 hours to remove volatile ingredients, thenis cooled and crushed to a granular form. Portions of the product areinjection molded and tested for tensile strength, elongation and impactstrength. The resulting test pieces have excellent tensile and impactstrength and elongation as compared to those described in U.S. Pat. No.3,426,103.

In accordance with the foregoing procedures, several similarcompositions are prepared using poly-isoprene (cis-1,4) rubber,styrene-butadiene block copolymer rubber, butadiene/acrylonitrilerubber, ethylene/propylene rubber, and natural rubber instead of thestereospecific polybutadiene rubber as the rubber component. Injectionmoldings of the resulting compositions also exhibit excellent tensilestrength, elongation and impact strength.

What is claimed is:
 1. A normally solid polymer of anar-halo-ar-(t-alkyl)styrene wherein halo is chloro, bromo or fluoro andtertiary alkyl has from 4 to 8 carbon atoms and is in a ring positionpara or meta to the ethylentically unsaturated group of thear-halo-ar-(t-alkyl)styrene, said polymer capable of being fabricatedinto useful articles according to known techniques for fabricatingconventional styrene polymers.
 2. The polymer of claim 1 wherein thear-halo-ar-alkylstyrene is represented by the general structuralformula: ##STR4## wherein R₁ is hydrogen or methyl; R₂ is tertiary alkylhaving from 4 to 8 carbon atoms and is in a ring position para or metato ##STR5## X is chloro or bromo and is in an open ring position; and ais one or two.
 3. The polymer of claim 1 wherein thear-halo-ar-alkylstyrene is represented by one of the followingstructural formulas: ##STR6## wherein R₁ is hydrogen; R₂ is t-butyl,t-pentyl, t-hexyl, t-heptyl or t-octyl; and X is chloro or bromo.
 4. Thepolymer of claim 1 wherein the ar-halo-ar-(t-alkyl)styrene is a2-halo-4-(t-alkyl)styrene or 2-halo-5-(t-alkyl)styrene.
 5. The polymerof claim 1 wherein the ar-halo-ar-alkylstyrene is selected from thegroup consisting of 2-bromo-4-(t-butyl)styrene,2-chloro-4-(t-butyl)styrene, 2-bromo-5-(t-butyl)styrene,2-chloro-5-(t-butyl)styrene.
 6. The polymer of claim 1 which is acopolymer of an isometric mixture of ar-halo-ar-(t-alkyl)styrenes. 7.The polymer of claim 1 which is a copolymer of2-bromo-4-(t-butyl)styrene and 2-bromo-5-(t-butyl)-styrene or copolymerof 2-chloro-4-(t-butyl)styrene and 2-chloro-5-(t-butyl)styrene.